Company email (May 2016):
"Unfortunately all of our cask beers are unsuitable for vegans as they are fined with isinglass. However, ALL of our keg and bottle products are suitable as they are unfined."

Company tweet (@SWBAndy) (January 2013): [regarding CASKED beers]
[The info on your page comes from their website shop, which refers to their bottled beers. I was a bit dubious about their cask ale so tweeted the Director Andy, as follows: "Hi Andy Can you tell me if all your cask ale is suitable for vegans ie un-fish-fined?"]
"The dark beers are all unfined. At the moment pale ales are fined unless stated on the pumpclip as unfined. Hope that helps"

From their website:
"These beers are unfiltered, unpasteurised & unadultered. They are not bottle conditioned either so you get to drink the entire contents of the bottle with no worries about sediment.
We have carefully carbonated each beer to a level that suits each individual beer. The beer is in it's purest state, we don't even use finings so all our bottled beers are suitable for Vegans too!"